Pixel-based correction for Charge Transfer Inefficiency in the Hubble Space Telescope Advanced Camera for Surveys
Abstract
Charge Transfer Inefficiency (CTI) due to radiation damage above the Earth's atmosphere creates spurious trailing in Hubble Space Telescope (HST) images. Radiation damage also creates unrelated warm pixels – but these happen to be perfect for measuring CTI. We model CTI in the Advanced Camera for Surveys (ACS)/Wide Field Channel and construct a physically motivated correction scheme. This operates on raw data, rather than secondary science products, by returning individual electrons to pixels from which they were unintentionally dragged during readout. We apply our correction to images from the HST Cosmic Evolution Survey (COSMOS), successfully reducing the CTI trails by a factor of ~30 everywhere in the CCD and at all flux levels. We quantify changes in galaxy photometry, astrometry and shape. The remarkable 97 per cent level of correction is more than sufficient to enable a (forthcoming) reanalysis of downstream science products and the collection of larger surveys.
Additional Information
© 2009 The Authors. Journal compilation © 2009 RAS. Accepted 2009 September 1; received 2009 August 31; in original form 2009 August 5. The authors gratefully thank Chris Bebek, Paul Bristow, Marissa Cevallos, Nick Cross, Kyle Dawson, Andy Fruchter, Nigel Hambly, Mike Lampton, Michael Levi, Max Mutchler, Natalie Roe, George Seabroke, Suresh Seshadri, Patrick Shopbell, Tim Schrabback and Roger Smith for sharing their expertise. The HST ACS CTI calibration programme is funded through NASA grant HST-AR-10964. The HST COSMOS Treasury programme was funded through NASA grant HST-GO-09822 with P.I. Nick Scoville. RM is supported by STFCAdvanced Fellowship PP/E006450/1 and FP7 grant MIRG-CT-208994. AL acknowledges support from the Chamberlain Fellowship at LBNL and from the Berkeley Center for Cosmological Physics. This work was based on the observations with the NASA/ESA HST, obtained at the Space Telescope Science Institute, which is operated by AURA Inc, under NASA contract NAS 5-26555.Attached Files
Published - Massey2010p6694Mon_Not_R_Astron_Soc.pdf
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Additional details
- Eprint ID
- 17262
- Resolver ID
- CaltechAUTHORS:20100121-093145806
- PP/E006450/1
- Science and Technology Facilities Council (STFC)
- MIRG-CT-208994
- Seventh Framework Programme (FP7)
- Chamberlain Fellowship at LBNL
- Berkeley Center for Cosmological Physics
- HST-AR-10964
- NASA
- HST-GO-09822
- NASA
- NAS 5-26555
- NASA
- Created
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2010-01-26Created from EPrint's datestamp field
- Updated
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2021-11-08Created from EPrint's last_modified field